Who Ruled Earth before the Dinosaurs? the 'Ugliest Fossil Reptiles'

Who Ruled Earth before the Dinosaurs? the 'Ugliest Fossil Reptiles'

Article excerpt

Before the dinosaurs succeeded to the throne, a group of
prehistoric reptiles reigned over the Earth.

Pareiasaurs, stocky herbivores that have been called the "ugliest
fossil reptiles," are less well-known than their successors. But
"they represent the pinnacle of the evolution of vertebrates on land
before the dinosaurs," Michael Benton, a vertebrate paleontologist
at the University of Bristol, tells The Christian Science Monitor in
an interview.

And understanding more about these animals could provide insight
into the world leading up to one of the largest extinctions ever to
rock the Earth: the end-Permian mass extinction.

Pareiasaurs roamed the planet for some 10 million years leading
up to the extinction event some 252 million years ago. That
extinction is thought to have wiped out 90 percent of species living
at the time, creating the void that the dinosaurs and many other
animals would occupy. Its causes remain a matter of debate. Any
insight into pareiasaurs could help scientists better understand
that enormous event.

Prehistoric cousinsFossils of the animal have been unearthed in
various regions across the globe including Russia, South Africa, and
China. But little has been known about how these different specimens
relate to each other.

They're all closely related, Dr. Benton says after further
investigating the trove of fossils in China.

"People had thought that maybe the Chinese ones were a special
little side branch of evolution. In fact, they're not," Benton says.

Furthermore, the Chinese specimens were thought to represent six
disparate species of pareiasaurs, but Benton's research finds that
there were actually just three, according to a paper published
Friday in the Zoological Journal of the Linnean Society.

"We can use this information as a basis for understanding how
pareiasaurs migrated and colonized different parts of the world,"
Linda Tsuji, curator of natural history at the Royal Ontario Museum
who was not part of the study, tells the Monitor in an email.

At the time, the Earth had one single supercontinent: Pangea. So
it's not all that surprising that pareiasaur fossils found in
present-day China, Russia, and South Africa were close cousins.
"Even these large, lumbering creatures, which I'm sure couldn't have
moved very fast, were able to stomp around the world," Benton says.

Life in the late Permian"Despite being important, distinctive (I
would be unwilling to call them ugly) members of land ecosystems
before the age of dinosaurs, pareiasaurs are relatively poorly
understood," Dr. …